Conventionally, in this kind of laser scan type fluorescence microscope, a picture has been obtained by detecting light emanated from a sample wherein laser light condensed at a minute spot domain of the sample is scanned by scanning means, such as Galvano mirror, in addition to general observation of a microscope.
FIG. 1 is an outline block diagram showing one conventional example of a laser scan type confocal fluorescence microscope.
The laser scan type confocal fluorescence microscope of FIG. 1 comprises a laser light source section 51, an objective optical system 53 which condenses excitation light from a laser light source section 51 on a sample 52, a scanning means 54 which scans a surface of the sample 52 with the excitation light from the laser light source section 51, a pupil projection lens 55 arranged between the scanning means 54 and the objective optical system 53, a detection optical system 56 for detecting fluorescence which emanates from the sample 52 and passes the objective optical system 53 and the pupil projection lens 55.
The laser light source section 51 has a laser light source 51a, a collimating optical system including lenses 51b and 51d and a pinhole 51c, and a dichroic mirror 51e. 
The objective optical system 53 has an objective lens 53a and an image forming lens 53b for forming an intermediate image of the sample 52. Moreover, a back focal position of the objective lens 53a is made conjugate with a position near the scanning means 54 by the image forming lens 53b and the pupil projection lens 55.
The scanning means 54 is configured as a proxy type Galvano mirror having Galvano mirrors 54a and 54b. 
The detection optical system 56 has a dichroic mirror 56a, a barrier filter 56b, a lens 56c, and a confocal pinhole 56d and a light receiving optical sensor 56e, such as a photomultiplier.
Furthermore, the microscope of FIG. 1 has a dichroic mirror 57 which leads the fluorescence from the sample 52 to the detection means 56 while leading the excitation light from the light source section 51 to the sample 52, a mirror 59 which deflects the light transmitted through the pupil projection lens 55 to the image forming lens 53b, an eyepiece optical system 60 for observing the image of the sample 52, and a fluorescence lighting optical system 61 used in normal fluorescence observation.
Thus, in the laser scan type confocal fluorescence microscope as constituted in FIG. 1, the excitation light emanating from the laser light source 51a is condensed at the pinhole 51c by the lens 51b, and then is converted into a beam of parallel rays by the lens 51d. Then, this excitation light is led to the proxy type Galvano mirror section, which is the scanning means 54, via dichroic mirrors 51e and 57, and the beam of rays of it is shifted two dimensionally in reference to the optical axis by each rotation of Galvano mirrors 54a and 54b, to be formed as a primary image as being focused on the intermediate image position 58 through the pupil projection lens 55. The excitation light condensed at the intermediate image position 58 is incident on the sample 52 at a minute spot via the mirror 59, the image forming lens 53b, and the objective lens 53a. At this time, the surface of the sample 52 is scanned with the excitation light by the scanning means 54.
The back focal position of the objective lens 53a is projected by the image forming lens 53b and the pupil projection lens 55 near the proxy type Galvano mirror which is the scanning means 54.
Fluorescence excited on the sample 52 by irradiation with the excitation light is led to the detection optical system 56 via the objective lens 53a, the image forming lens 53b, the pupil projection lens 55, the scanning means 54, and the dichroic mirror 57. Then, a wavelength separation is carried out by the dichroic mirror 56a, and only fluorescence that passes through the confocal pinhole via the barrier filter 56b and the lens 56c is detected by the light receiving optical sensor 56e, such as a photomultiplier.
In carrying out a normal fluorescence observation through the eyepiece optical system 60, a fluorescence lighting optical system 61 equipped with a different light source 61a from the laser light source 51a is used. Excitation light emanating from the light source 61a is transmitted through a lens 61b and a filter 61c, is reflected by the dichroic mirror 61d, and illuminates the sample 52 through the objective lens 53a. Fluorescence excited on the sample 52 by irradiation with the excitation light is condensed by the objective lens 53a, is subjected to wavelength separation by the dichroic mirror 61d arranged in the fluorescence lighting optical system 61, and is observed via the prism 60a and the eyepiece 60b of the eyepiece optical system 60 through the barrier filter 61e. 
Such a conventional laser-scan-type confocal fluorescence microscope is excellent in resolution, and it has an advantage that light from other than a minute spot to be observed can be eliminated. Thus, it is useful for carrying out an intracellular functional elucidation etc.
However, in the laser scan type confocal fluorescence microscope, the equipment itself becomes large since it is necessary to add an optical system such as a pupil projection lens 55 and a scanning means 54 mentioned above etc., in addition to an optical system used for a normal fluorescence observation, such as an objective lens 53a and an image forming lens 53b. 
That is, generally as for the optical system of a laser-scan type confocal fluorescence microscope, the focal length of an image forming lens is such long as around 180 mm. Consequently, a total length from a sample to the scanning means arranged near a conjugate position of a pupil of an objective lens becomes 400-500 mm, to enlarge the whole equipment.
For this reason, a confocal fluorescence observation and a fluorescence observation become possible only in case that the sample is arranged on a stage of a microscope.
Moreover, when a confocal fluorescence observation is actually performed to a rat, a small animal or a cell under a cultivation environment where it is alive (in vivo), there is a restriction that the observation environment must be built on the stage. Furthermore, a laser scan type confocal fluorescence microscope is generally designed to perform observation in a state where the optical axis of an objective lens becomes perpendicular to a surface of the stage. Therefore, it is difficult to observe the sample from a slant direction. Moreover, it is difficult to perform observation upon leaning the whole laser scan type confocal fluorescence microscope to the sample or leaning the sample and the stage.